Inter-rater reliability of the Australian Spasticity Assessment Scale in poststroke spasticity

Abstract

To investigate the inter-rater reliability of the Australian Spasticity Assessment Scale (ASAS) in adult stroke patients with spasticity, two experienced clinicians rated the elbow flexor, wrist flexor, and ankle plantar flexor spasticity by using the ASAS in 85 persons with stroke. Unweighted and weighted (linear and quadratic) kappa statistics were used to calculate the inter-rater reliability for each muscle group. Unweighted kappa coefficients for elbow flexors (n = 83), wrist flexors (n = 80), and ankle plantar flexors (n = 77) were 0.67, 0.60, and 0.55, respectively. Linear and quadratic weighted kappa coefficients, respectively, were 0.77 and 0.87 for elbow flexors, 0.72 and 0.82 for wrist flexors, and 0.72 and 0.85 for ankle plantar flexors. The raters never disagreed by more than a single score in the rating of elbow flexors. On the contrary, the raters disagreed by more than a single score in three patients in the rating of ankle plantar flexors and in one patient in the rating of wrist flexors. The results suggested that inter-rater reliability of the ASAS differed according to the spastic muscle group assessed and the statistical method used. The strength of the agreement on the ASAS, an ordinal scale, ranged from good to very good when the weighted kappa values were considered.